1. Field of the Invention
The present invention relates to a keyboard device for an electronic keyboard musical instrument such as an electronic piano which has keys and hammers each pivotally movable in response to depression on an associated key.
2. Description of the Prior Art
FIGS. 1 through 3 illustrate an exemplary keyboard device of a conventional electronic piano. The illustrated keyboard device 51 comprises a chassis 2; a large number of keys 3 (one each of white key 3a and black key 3b are illustrated) arranged side by side in the lateral direction (in the depth direction in FIG. 10) on the chassis 2; a large number of hammers 4 (only one of which is illustrated) each pivotally movable in response to depression of an associated key 3. The chassis 2 is made of a steel plate or the like which is punched out and bent through a press work. Each of the keys 3 is pivotably supported at the center thereof by a balance pin 6 implanted on the chassis 2.
The hammer 4 is supported by a hammer rail 52 coupled to a rear end portion of the chassis 2 through a fulcrum member 53. The hammer rail 52 is made of a press-worked steel plate or the like, as is the case with the chassis 2. The hammer rail 52 extends in the lateral direction to cover all the hammers 4, and fixed to the chassis 2 at a plurality of locations with screws 61, and also fixed to a keybed 5 with screws 62. Also, as illustrated in FIG. 3, the hammer rail 52 is formed with a large number of vertical mounting holes 52a, 52b arranged side by side in the lateral direction for mounting the fulcrum members 53.
A large number of fulcrum members 53 are provided one for each hammer 4. The fulcrum members 53 are made, for example, of synthetic resin moldings by injection molding. As illustrated in FIG. 2, each of the fulcrum members 53 comprises a body 53a in the shape of inverted C in cross-section, which has an opened front surface; an upper and a lower engaging protrusion 53b, 53c (see FIG. 3) formed on the back surface of the body 53a; shaft holes 53d formed in a left and a right wide wall of the body 53a such that they are open to the front face each other; a key switch mount 53f formed on the top surface of the body 53a and having an engaging recess 53e. 
Then, as illustrated in FIG. 3, each of the fulcrum members 53 is mounted on the hammer rail 52 by fitting the upper and lower protrusions 53b, 53c into the upper and lower mounting holes 52a, 52b of the hammer rail 52, respectively. Also, as illustrated in FIG. 2, engaged protrusions 4a (only one of which is illustrated) protruding on both sides of the hammer 4 are fitted into the shaft holes 53d of the fulcrum member 53 mounted on the hammer rail 52 in the foregoing manner, thereby pivotably supporting the hammer 4 by the fulcrum member 53. In this structure, both side walls of the fulcrum member 53 define a space for allowing pivotal movements of the hammer 4, and serve to prevent the hammer 4 from shifting in lateral directions. In addition, the hammer 4 is carried on a rear end portion of the associated key 3, so that depression on the key 3 causes the hammer 4 to pivotally move to apply the key 3 with a touch weight similar to that of an acoustic piano.
A plurality of action ribs 54, for example, arranged in octaves, are attached to the hammer rail 52 with a large number of screws 63 (only two of which are illustrated) at predetermined intervals in the lateral direction. Stopper rails 55 are attached to the leading ends of the action ribs 54 with a large number of screws 64 (only two of which are illustrated). The stopper rails 55 extend in the lateral direction to cover all the hammers 4. These action ribs and stopper rails 55 are made of press-worked steel plates or the like, as is the case with the hammer rail 52.
Each of the stopper rails 55 comprises a stopper 14 for restricting the associated hammer 4 from pivotally moving upward; and a key switch 15 for detecting information on depression on the associated key 3. The stopper 14 extends in the lateral direction to cover the whole length of the hammer 4, and is made of foamed urethane or the like. The key switch 15 is mounted to the stopper rail 55 with screws (not illustrated), with its printed board 16 having a rear end portion inserted into the engaging recess 53e of the fulcrum member 53.
The conventional keyboard device 51 described above requires a large number of parts because the hammer rail 52, action ribs 54 and stopper rails 55 are individually assembled into the keyboard device 51, and these components must be coupled to one another with a large number of screws 63, 64. Also, the supporting members 53 for supporting a large number of hammers 4 are required in a number equal to the number of hammers 4, resulting in the need for a quite large number of parts. In addition, such a large number of supporting members 53 must be manually mounted to the hammer rail 52 one by one. Consequently, the conventional keyboard device 51 requires a quite large number of parts as well as assembling steps, causing an increased manufacturing cost.
Furthermore, the hammer rail 52, action ribs 54 and stopper rails 55 are all made of press-worked steel plates or the like, making it difficult to achieve a high assembly accuracy, due to a low dimensional accuracy of each component and an additional assembly errors. As a result, the hammers 4, stoppers 14, key switches 15 and so on, attached to these components, are also susceptible to large mounting errors, and therefore require a delay for adjustments, contributing to an increased manufacturing cost as well. Moreover, the supporting member 53 is mounted to the hammer rail 52 by fitting the engaging protrusions 53b, 53c of the supporting member 53 into the mounting holes 52a, 52b of the hammer rail 52, while the supporting member 53 is made of a synthetic resin molding. This inevitably causes variations, to some degree, in dimensional accuracy of the engaging protrusions 53b, 53c, and therefore in a positional relationship and a dimensional relationship between the engaging protrusions 53b, 53c and the mounting holes 52a, 52b among the fulcrum members 53, leading as well to a lower mounting accuracy of the hammers 4.
Also, since the stopper 14 is attached to the stopper rail 55 supported over a plurality of action ribs 54 arranged at intervals, the action ribs 54 are susceptible to vibrations due to collision of the hammer 4 with the stopper 14, possibly causing noise.
The present invention has been made to solve the problems as mentioned above, and it is an object to provide a keyboard device for an electronic keyboard musical instrument which permits a significant reduction in the number of parts constituting hammer supporting members and the number of assembling steps required therefor, thereby reducing a manufacturing cost, and also permits hammers to be mounted in a high mounting accuracy to eliminate noise.
To achieve the above object, a keyboard device for an electronic keyboard musical instrument according to a first aspect of the present invention includes a chassis; a hammer rail made of an aluminum extrudate, and coupled to the chassis; a plurality of keys pivotably supported by the chassis; a plurality of hammers each provided for each of the plurality of keys, wherein each hammer is pivotably supported by the hammer rail and configured to pivot in response to depression on a key associated therewith; and a stopper mounted to the hammer rail for restricting a pivotal movement of a hammer caused by depression on a key associated with the hammer.
According to this keyboard device for an electronic keyboard musical instrument, the hammers are supported by the hammer rail made of an aluminum extrudate, to which the stopper is mounted for restricting pivotal movements of the hammers. In other words, the hammer rail of the keyboard device has in combination a function of the hammer rail for supporting the hammers; a function of stopper rails for mounting the stopper; and a function of action ribs for coupling both rails, among functions provided by the aforementioned conventional keyboard device. In this way, since the conventional hammer rail, plurality of action ribs, and stopper rails are replaced with the single hammer rail, the number of parts can be reduced correspondingly. In addition, the number of assembling steps can be largely reduced by virtue of complete elimination of numerous screwing works for assembling the components, as required in the conventional keyboard device.
Since the hammer rail is comprised of an aluminum extrudate, the dimensional accuracy of the hammer rail is higher than the conventional counterpart made of a press-worked steel plate or the like, without any assembling errors added to the resulting keyboard device. As a result, since the hammers and stopper are mounted on the hammer rail in a higher mounting accuracy, adjustments therefor are eliminated or facilitated. Further, unlike the conventional keyboard device in which the stoppers are mounted on the stopper rail supported by a plurality of action ribs arranged at intervals, the keyboard device of the present invention can limit vibrations due to collision of the hammer with the stopper and prevent noise caused by the vibrations.
In the foregoing keyboard device, the hammer rail preferably includes a single hammer rail extending in a direction in which the plurality of hammers are arranged side by side for supporting all the hammers.
In this structure, since the single hammer rail alone is provided for the whole keyboard device, the number of parts can be further reduced. In addition, the number of assembling steps can be largely reduced by virtue of complete elimination of numerous screwing works for assembling the components of the hammer rail, and the mounting accuracy can be further increased for the hammers and so on.
Preferably, the hammer rail includes a fulcrum shaft integrally formed therewith, wherein the fulcrum shaft extends in a lengthwise direction of the hammer rail in engagement with the plurality of hammers for supporting the same.
In this structure, since the fulcrum shaft in engagement with the hammers for supporting is also molded integrally with the hammer rail, the number of parts and the number of assembling steps can be largely reduced as compared with the conventional keyboard device in which a fulcrum member is provided for each hammer, and the mounting accuracy can be further increased for the hammer.
Preferably, the keyboard device for an electronic keyboard musical instrument further includes key switches each for detecting information on depression on an associated keys, and a key switch mount integrally molded with the hammer rail, extending in a lengthwise direction of the hammer rail for mounting the key switch thereon.
In this structure, since the key switch mount for mounting the key switches thereon for detecting information on depression on the plurality of keys is also integrally molded with the hammer rail, the mounting accuracy can be increased for the key switch.
In this event, the hammer rail preferably has a hollow cross-section.
The provision of the hollow hammer rail permits a reduction in weight and material cost as well as a sufficient rigidity ensured to support an impact due to collision of the hammer with the stopper.
To achieve the above object, a keyboard device for an electronic keyboard musical instrument according to a second aspect of the present invention includes a chassis; a hammer rail coupled to the chassis; a plurality of keys arranged side by side in a lateral direction and pivotally supported by the chassis; a plurality of hammers arranged side by side in the lateral direction, each of which is provided for each of the keys, and configured to pivot in response to depression on the key associated therewith; and a fulcrum shaft made of an aluminum extrudate integrally with the hammer rail to extend in the lateral direction in engagement with the plurality of the hammers for pivotably supporting the hammers.
According to this keyboard device for an electronic keyboard musical instrument, since a plurality of hammers are supported by the single fulcrum shaft made of an aluminum extrudate, the number of parts and the number of assembling steps can be reduced as compared with the conventional keyboard device in which a supporting member is provided for each hammer. For the same reason, variations in the fulcrum positions among the hammers are reduced as compared with the conventional keyboard device in which fulcrum members are molded and mounted on the hammer rail on a one-by-one basis, thereby making it possible to mount the hammers in a higher mounting accuracy.
In the foregoing keyboard device, the fulcrum shaft preferably includes a single fulcrum shaft for supporting all the hammers.
In this structure, since the single fulcrum shaft is provided for the whole keyboard device, it is possible to largely reduce the number of parts and the number of assembling steps as well as further increase the mounting accuracy for the hammer.
Preferably, the hammer rail is molded integrally with the fulcrum shaft.
In this structure, since the hammer rail for supporting the hammers through the fulcrum shaft is integrally molded with the fulcrum shaft as an aluminum extrudate, the number of parts and the number of assembling steps can be further reduced as compared with the conventional keyboard device in which such components are individually formed and assembled into a hammer rail. For the same reason, saccadic movements of the fulcrum shaft itself are eliminated to prevent noise, generated when a key is depressed, caused by such saccadic movements.
Preferably, the keyboard device for an electronic keyboard musical instrument further includes a fulcrum member formed of a synthetic resin molding and mounted to the fulcrum shaft to surround the fulcrum shaft, wherein the plurality of hammers are engaged with and supported by the fulcrum member.
Generally, a molding made of synthetic resin, constituting the fulcrum member, exhibits a higher molding accuracy than the aluminum extrudate constituting the fulcrum shaft. Therefore, according to the foregoing structure, the mounting accuracy can be further increased for the hammers by supporting a plurality of hammers by the single fulcrum member mounted on the fulcrum shaft, as compared with hammers directly supported by a fulcrum shaft. Also, the high molding accuracy of the fulcrum member limits saccadic movements of the hammers. The synthetic resin having a higher lubricity than aluminum can help ensure smooth pivotal movements of the hammers, thereby preventing noise generated from the supporter of the hammers.
In the foregoing structure, preferably, the keyboard device for an electronic keyboard musical instrument further includes a plurality of lateral shift stoppers each provided every predetermined number of the hammers near the fulcrum shaft for restricting lateral movements of the hammers.
In this structure, since the plurality of lateral shift stoppers restrict lateral movements of the hammers, the hammers can be prevented from shifting in the lateral direction. In other words, the lateral shift stoppers can solve the problem of lateral shift experienced by the hammers caused by the extension of the fulcrum shaft in the lateral direction for supporting a plurality of hammers.